Who should replace Rosberg at Mercedes?

Formula 1 world champion Nico Rosberg's shock retirement means a plum seat on the 2017 grid has now opened up.

The chance to join Lewis Hamilton at Mercedes will be at the top of the priority list for most of the field, even those who last week thought their plans were firmly locked in.

But what should Mercedes do? Look in-house for a young gun? Move heaven and earth for the very best? Poach talent from elsewhere? Or maybe even tempt back someone who had called time on F1?

Here are the Autosport team's best picks for the second Mercedes seat.

PASCAL WEHRLEIN
Ben Anderson, Grand Prix Editor (@BenAndersonAuto)

Mercedes junior Pascal Wehrlein is the most logical choice, certainly in the short term.

Wehrlein did a superb job as a rookie at Manor this year, making Q2 five times in what was fundamentally the slowest car on the grid, and scoring an unlikely point in July's Austrian Grand Prix.

It was Wehrlein's performance in qualifying at the Red Bull Ring - where he put his Manor inside the top 10 in Q1 before qualifying a season's best 12th - that prompted Mercedes team boss Toto Wolff to declare Wehrlein a "special boy".

Fellow Mercedes junior Esteban Ocon somewhat stole Wehrlein's thunder by earning promotion to Mercedes customer team Force India for 2017, after just seven races with Manor.

But that was not Mercedes' decision. Force India simply rates Ocon more highly, after testing both drivers and being particularly impressed by Ocon's performance in last season's post-Austrian GP young driver sessions.

Wehrlein was the better Manor driver before Ocon joined the team, and he was overall still the better performing of the two after Ocon joined - certainly in qualifying.

The 2015 DTM champion is very highly rated within Mercedes, and Wehrlein knows the team well already, having been its reserve driver and completed seven-and-a-half days of testing with the squad over the past three seasons, plus 2017 Pirelli tyre testing this year.

Wehrlein is a Mercedes junior for a good reason. There is simply no need for the world champion squad to dive into the driver market so late in the day, and pay over the odds to buy a star driver out of his contract.

Mercedes already has Lewis Hamilton on the books remember.

What happens after that is anyone's guess. Sebastian Vettel, Kimi Raikkonen, Fernando Alonso, Valtteri Bottas, Sergio Perez, Carlos Sainz Jr, and Jenson Button (if McLaren lets its option lapse) are all out of contract at the end of 2017...

SEBASTIAN VETTEL
Mitchell Adam, International Editor (@DrMitchellAdam)

Write a list of the best three Formula 1 drivers of this generation and tell me Lewis Hamilton and Sebastian Vettel aren't on that list.

And then tell me you wouldn't be massively excited and intrigued by the prospect of having them both racing at the same team and - assuming Mercedes doesn't forget how to make F1 cars this winter - fighting for wins and world championships. They would both back themselves to win.

As slim as the prospect would be, it would be just what F1 needs. Between them, Vettel and Hamilton have won seven of the nine drivers' titles awarded since 2008 and redefined what it means to be a driver in the modern era. And while Mercedes is a global company, a German of Vettel's profile to replace Rosberg would also be a good fit.

How Vettel might get there would be interesting in itself. He is under contract to Ferrari until the end of next season, but after a dream start in 2015, Ferrari regressed this year. Pre-season talk of a title challenge was followed by a winless campaign, and moments (on and off-track) that resembled Ferrari before Michael Schumacher arrived.

A big part of Vettel would want to stay and see the project through to Schumacher-style success. But that same Vettel will have also watched some of the best years of Fernando Alonso's career wasted in underperforming Ferraris.

We all want to see the best drivers in the best cars; it's worth a check of that contract and a message to Toto, Sebastian.

FERNANDO ALONSO
Kevin Turner, Autosport Magazine Editor, (@KRT917)

If you were naming the top talents in F1 over the last decade, you'd probably come up with Lewis Hamilton, Sebastian Vettel and Fernando Alonso.

It's a travesty that Alonso, the man who ended Michael Schumacher's reign, hasn't won the championship for a decade and has 'only' two titles, compared to four for Vettel and three (with a good chance of more) for Hamilton.

Ferrari rarely gave Alonso a car worthy of his talents during his five years there and yet twice he nearly took the championship. McLaren-Honda has not been able to provide Alonso with anything close to a podium contender and, although the combination is improving, time must be running out for the 35-year-old.

Another title shot would almost be guaranteed if Alonso took Rosberg's Mercedes seat, which the Spaniard surely deserves. But perhaps even better than that, we would get to see Hamilton v Alonso part two.

Although ultimately it cost both drivers and the team, the rivalry between the two at McLaren in 2007 was explosive. Both have come a long way since then, but it's hard not to like the idea of two of F1's best drivers going at it once again.

Button, who has partnered both, reckons Alonso is the most complete team-mate he has ever had, while Hamilton will surely be as hungry as ever after being outscored by a driver in the same car for only the second time in his F1 career.

It's not the most realistic choice - and Alonso has another year on his McLaren contract - but it would be the most exciting.

DANIEL RICCIARDO
Edd Straw, Editor-in-Chief, (@EddStrawF1)

Were you to eliminate all questions of contract, as a top grand prix team Mercedes would ideally want to bring in the best available driver, and Daniel Ricciardo is that man.

While Red Bull team-mate Max Verstappen has deservedly monopolised the plaudits this year, Ricciardo is the Red Bull driver that ticks all the boxes. He's also a hugely accomplished driver eminently capable of winning the world championship.

At 27, Ricciardo is the fully-rounded package Mercedes needs to complement Lewis Hamilton. His reaction to losing certain victory in the Monaco Grand Prix to a pitstop blunder shows that below the cheery exterior is the heart of a steely competitor who is absolutely determined to win a world championship. Rosberg's talk about the commitment needed to perform in the heat of a title fight reveals how vital that is.

He's incredibly fast, as he has shown by winning races and taking a pole position despite never being in the best package in F1. He can overtake, to the point where he occasionally suggests most of his rivals would have failed to emulate his passes - showing the swagger of a champion.

The Australian would be incredibly difficult - and costly - to get out of his contract, so it's a very long shot and might not even be possible. But if Mercedes wants to go for the best, Ricciardo should be number one on the list.

ESTEBAN OCON
Glenn Freeman, Autosport.com Editor (@Glenn_Autosport)

As tempting as the idea of one of Fernando Alonso, Daniel Ricciardo, Max Verstappen or Sebastian Vettel slotting in alongside Lewis Hamilton at Mercedes next year is, let's take the slightly less fun route and assume contracts (and the potential for a potent Adrian Newey-designed Red Bull to new regulations) rule those dream scenarios out.

Mercedes had two juniors on the F1 grid in the second half of 2016, with Esteban Ocon alongside Pascal Wehrlein at Manor from mid-season.

Yes, Ocon is already in place at Force India for next year, but if Mercedes is able to hold any sway - or can enjoy a sensible negotiating position - with a rival team it surely has to be one where it supplies engines.

Mercedes claims it wasn't involved in Force India's decision to choose Ocon over Wehrlein as Nico Hulkenberg's replacement, but surely if it felt that was a poor call from the Silverstone-based team it would have sent it a friendly nudge in the other direction.

Ocon's Force India deal also confirms Mercedes managed to keep Renault's claws out of the Frenchman, who started the year clad in yellow on reserve driver duties with a potential tug-of-war for his services on the horizon.

When you throw in that Ocon is a Verstappen-beater from their time together in Formula 3 (granted, it was the Dutchman's first season of car racing), the case for Mercedes extracting him from Force India is compelling.

It's sooner than Mercedes would have liked to be putting its next hope into one of its own F1 cars, but as Hamilton and Verstappen have proven in the last decade, bold decisions can be rewarded.

Ocon is the way to go, and he can be more than just a seat-warmer until bigger names are out of contract.

CARLOS SAINZ JR
Scott Mitchell, Features Editor (@ScottAutosport)

Red Bull's two blockbusting talents Daniel Ricciardo and Max Verstappen would be at the front of any team's queue if everyone on the grid was a free agent. The reality is they aren't available.

Step forward Carlos Sainz Jr, one of the absolute star performers of 2016. After a solid start alongside Verstappen at Toro Rosso, Sainz comprehensively outperformed the demoted Daniil Kvyat in their 17 races together, beating him 42-4 on the scoreboard after notching eight top 10 results to Kvyat's two.

The Spaniard's form has been rewarded with a third season in Red Bull's junior stable, and while it is good news he will remain on the grid it is not the step forward he will want for his career.

It's also not what he deserves. Momentum is crucial in motorsport, particularly when you get into F1, and Sainz has more that any stage of his career so far.

Sainz is likely to be on a standard rolling junior contract with Red Bull, so his 2017 commitment should be a one-year deal. Surely he represents the best 'buyout' option on the table for Mercedes?

Red Bull would not let Sainz go easily. But at the same time, will it be completely desperate to keep him? There is no room at the top table thanks to the age and ability of Ricciardo and Verstappen, while bubbling under are the likes of Pierre Gasly, Red Bull's first GP2 champion.

Red Bull's cupboard is well-stocked, and that means it's no better time for Mercedes to go pantry-raiding.

VALTTERI BOTTAS
Marcus Simmons, Autosport Magazine Deputy Editor (@MarcusSimmons54)

Anyone who's read my coverage of the junior single-seater ranks over the past three years will not be surprised to learn that I'm in agreement with Glenn Freeman above: I rate Esteban Ocon extremely highly - he beat Max Verstappen in the 2014 Formula 3 season after all ­- and would love to see him in the Mercedes Formula 1 hot seat next year against Lewis Hamilton.

That's my heart speaking, but my head is suggesting that we shouldn't rule out Valtteri Bottas. He's done an extremely solid job at Williams over the past four seasons, and arguably deserves a chance to show what he could do at a top team. Furthermore, a certain Toto Wolff is part of his management team.

He'd have to break his contract with Williams, but surely a nice little sweetener on the team's Mercedes engine deal wouldn't be impossible to imagine.

This would then leave Williams with a slot to fill alongside Lance Stroll. That could very easily be Pascal Wehrlein, overlooked by Force India for 2017 in favour of Ocon, but whose form alongside the Frenchman at Manor this term indicates that he'd do a very tidy job further up the grid.

Then there's super-talented Brit George Russell to consider: he is thought to be part of the Mercedes junior programme, although the team has not admitted as such, and any move to an F1 race seat is certainly at least a year away - first he needs to perform (as he surely will) on his expected move to GP3 next season.

And what about Merc-contracted Felix Rosenqvist? Superb in everything he's done this year, surely he deserves at least a shot at an F1 tryout.

But it's good news that these names are being bandied around after F1 has spent too long with over-conservative teams picking the same old drivers.

JENSON BUTTON
Lawrence Barretto, F1 Reporter (@LawroBarretto)

Jenson Button looked like he was ready for life after Formula 1 when he stepped out of his McLaren cockpit in the Abu Dhabi Grand Prix and embraced his friends and family.

It has been tough going for the 2009 world champion in recent years. Scrapping around towards the back in '15 was no fun. This term it was the midfield but only for the minor points.

The prospect of doing what he wants, when he wants, is something Button craves - having been in F1 since 2000 - but the opportunity to drive for the three-time reigning world champion team would be a hard thing to turn down.

Of the drivers not tied into a race drive, Button has the most experience. He's easy to work with and would most likely grab the chance to have one final shot at winning a second world title.

The move would not rock the boat either, as Hamilton will most likely not feel threatened by Button's arrival. The pair worked effectively during three seasons at McLaren - where Button outscored his countryman over the course of that period.

Mercedes would need to come to an arrangement with McLaren, given Button is contracted for next season as a reserve with an option on the team's side for 2018.

But getting Button - who has never liked to use the word retirement - out of that contract will likely be easier, and cheaper, than trying to do the same for his more decorated or sought-after rivals.

A one-year deal would work for both sides, particularly as Vettel, Alonso and Valtteri Bottas will be out of contract at the end of 2017 while Mercedes juniors Esteban Ocon and Pascal Wehrlein will have another season of experience.